Multi-mode, multi-channel magnetic recording head and apparatus

ABSTRACT

In one embodiment, a drive-implemented method includes determining, by a tape drive, that a magnetic recording tape is compatible with a first format, the tape drive having an array of transducers including subarrays of the transducers positioned on opposite sides of an inner transducer, reading from or writing to the magnetic recording tape using the array in a first mode of operation corresponding to the first format, processing data using only transducers in the subarrays in the first mode of operation, and processing data using only a portion of transducers in each subarray in a second mode of operation corresponding to the second format. The first format specifies locations of data and a contiguous spare area on the tape and compatibility with a second format. The second format specifies a set of second active channels different than a set of first active channels specified by the first format.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to magnetic recording heads.

In magnetic storage systems, magnetic transducers read data from andwrite data onto magnetic recording media. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, the drive moves the magnetic tape over thesurface of the tape head at high speed. Usually the tape head isdesigned to minimize the spacing between the head and the tape. Thespacing between the magnetic head and the magnetic tape is crucial andso goals in these systems are to have the recording gaps of thetransducers, which are the source of the magnetic recording flux in nearcontact with the tape to effect writing sharp transitions, and to havethe read elements in near contact with the tape to provide effectivecoupling of the magnetic field from the tape to the read elements.

SUMMARY

A drive-implemented method, according to another embodiment, includesdetermining, by a tape drive, that a magnetic recording tape iscompatible with a first format, the tape drive having an array oftransducers including an inner transducer and subarrays of thetransducers positioned on opposite sides of the inner transducer,reading from or writing to the magnetic recording tape, by the tapedrive, using the array of transducers in a first mode of operationcorresponding to the first format, processing data, by the tape drive,using only the transducers in the subarrays in the first mode ofoperation, and processing data, by the tape drive, using only a portionof the transducers in each of the subarrays in a second mode ofoperation corresponding to the second format. The first format specifieslocations of data tracks on the magnetic recording tape, and acontiguous spare area on the magnetic recording tape. The first formatalso specifies compatibility with a second format. Moreover, the secondformat specifies a set of second active channels different than a set offirst active channels specified by the first format.

A drive-implemented method, according to yet another embodiment,includes determining, by a tape drive, that a magnetic recording tape iscompatible with a first format, the tape drive having an array oftransducers including an inner transducer and subarrays of thetransducers positioned on opposite sides of the inner transducer,reading from or writing to the magnetic recording tape, by the tapedrive, using the array of transducers in a first mode of operationcorresponding to the first format, processing data, by the tape drive,using only the transducers in the subarrays in the first mode ofoperation, and processing data, by the tape drive, using at least aportion of the transducers in each of the subarrays and the innertransducer in a second mode of operation. In addition, the first formatspecifies a set of first active channels, locations of data tracks onthe magnetic recording tape, and spare area on the magnetic recordingtape. The first format also specifies compatibility with a secondformat. Moreover, the second format specifies a set of second activechannels different than the set of first active channels specified bythe first format.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2A illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2B is a tape bearing surface view taken from Line 2B of FIG. 2A.

FIG. 2C is a detailed view taken from Circle 2C of FIG. 2B.

FIG. 2D is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIGS. 8A-8C are schematics depicting the principles of tape tenting.

FIG. 9 is a representational diagram of files and indexes stored on amagnetic tape according to one embodiment.

FIG. 10A is a representational view of an array of transducers,according to one embodiment.

FIGS. 10B-10G are representational views of active transducers within alarger array, according to various embodiments.

FIG. 11 is a partial representational view of a data band of a magneticrecording tape having spare area positioned centrally, according to oneembodiment.

FIG. 12A is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 12B is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 12C is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 12D is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 12E is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 12F is a representational view of a partial array of transducersaccording to one embodiment.

FIG. 13A is a flow diagram of a method according to one embodiment.

FIG. 13B is a flow diagram of a method according to one embodiment.

FIG. 14 is a partial representational view of a data band of a magneticrecording tape having spare area positioned proximate to a servo band,according to one embodiment.

FIG. 15 is a representational view of an array of transducers activatedaccording to a format, according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof.

In one general embodiment, an apparatus includes an array ofequally-spaced 2N+1 transducers, and at least two servo readerspositioned external to an outermost transducer of the array and on asame side thereof.

In another general embodiment, an apparatus includes an array of 2N+1transducers on a pitch. At least one of the transducers within the arrayis configured as a servo reader.

In another general embodiment, an apparatus includes an array oftransducers including an inner transducer and subarrays of thetransducers positioned on opposite sides of the inner transducer. Acontroller is coupled to the transducers. The controller is configuredto process data using only the transducers in the subarrays in a firstmode of operation. The controller is also configured to process datausing only a portion of the transducers in each of the subarrays in asecond mode of operation. The inner transducer is inactive in the secondmode of operation.

In another general embodiment, an apparatus includes an array of 2N+1transducers, and a controller directly electrically coupled to each ofthe transducers. The controller is configured to use transducers on onlyone side of a centerline of the array in one mode of operation.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may include at least oneservo channel and at least one data channel, each of which include dataflow processing logic configured to process and/or store information tobe written to and/or read from the tape 122. The controller 128 mayoperate under logic known in the art, as well as any logic disclosedherein, and thus may be considered as a processor for any of thedescriptions of tape drives included herein, in various embodiments. Thecontroller 128 may be coupled to a memory 136 of any known type, whichmay store instructions executable by the controller 128. Moreover, thecontroller 128 may be configured and/or programmable to perform orcontrol some or all of the methodology presented herein. Thus, thecontroller 128 may be considered to be configured to perform variousoperations by way of logic programmed into one or more chips, modules,and/or blocks; software, firmware, and/or other instructions beingavailable to one or more processors; etc., and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (internal or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or another device.

By way of example, FIG. 2A illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle a with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B may be made of the sameor similar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2B illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2B of FIG. 2A. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 32 data bands, e.g., with 16data bands and 17 servo tracks 210, as shown in FIG. 2B on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2C depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2C of FIG. 2B. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2C, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2A and 2B-2C together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2D shows a partial tape bearing surface view of complementarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write transducer 214 and the readers, exemplified by the readtransducer 216, are aligned parallel to an intended direction of travelof a tape medium thereacross to form an R/W pair, exemplified by the R/Wpair 222. Note that the intended direction of tape travel is sometimesreferred to herein as the direction of tape travel, and such terms maybe used interchangeably. Such direction of tape travel may be inferredfrom the design of the system, e.g., by examining the guides; observingthe actual direction of tape travel relative to the reference point;etc. Moreover, in a system operable for bi-direction reading and/orwriting, the direction of tape travel in both directions is typicallyparallel and thus both directions may be considered equivalent to eachother.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (−),cobalt zirconium tantalum (CZT) or Al—Fe—Si (Sendust), a sensor 234 forsensing a data track on a magnetic medium, a second shield 238 typicallyof a nickel-iron alloy (e.g., ˜80/20 at % NiFe, also known aspermalloy), first and second writer pole tips 228, 230, and a coil (notshown). The sensor may be of any known type, including those based onMR, GMR, AMR, tunneling magnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ≠45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also, note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹(δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used Liner Tape Open-(LTO)-compliant tape head spacing.The open space between the modules 302, 304, 306 can still be set toapproximately 0.5 to 0.6 mm, which in some embodiments is ideal forstabilizing tape motion over the second module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore, a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads. Moreover, unless otherwisespecified, processes and materials of types known in the art may beadapted for use in various embodiments in conformance with the teachingsherein, as would become apparent to one skilled in the art upon readingthe present disclosure.

As a tape is run over a module, it is preferred that the tape passessufficiently close to magnetic transducers on the module such thatreading and/or writing is efficiently performed, e.g., with a low errorrate. According to some approaches, tape tenting may be used to ensurethe tape passes sufficiently close to the portion of the module havingthe magnetic transducers. To better understand this process, FIGS. 8A-8Cillustrate the principles of tape tenting. FIG. 8A shows a module 800having an upper tape bearing surface 802 extending between oppositeedges 804, 806. A stationary tape 808 is shown wrapping around the edges804, 806. As shown, the bending stiffness of the tape 808 lifts the tapeoff of the tape bearing surface 802. Tape tension tends to flatten thetape profile, as shown in FIG. 8A. Where tape tension is minimal, thecurvature of the tape is more parabolic than shown.

FIG. 8B depicts the tape 808 in motion. The leading edge, i.e., thefirst edge the tape encounters when moving, may serve to skive air fromthe tape, thereby creating a subambient air pressure between the tape808 and the tape bearing surface 802. In FIG. 8B, the leading edge isthe left edge and the right edge is the trailing edge when the tape ismoving left to right. As a result, atmospheric pressure above the tapeurges the tape toward the tape bearing surface 802, thereby creatingtape tenting proximate each of the edges. The tape bending stiffnessresists the effect of the atmospheric pressure, thereby causing the tapetenting proximate both the leading and trailing edges. Modeling predictsthat the two tents are very similar in shape.

FIG. 8C depicts how the subambient pressure urges the tape 808 towardthe tape bearing surface 802 even when a trailing guide 810 ispositioned above the plane of the tape bearing surface.

It follows that tape tenting may be used to direct the path of a tape asit passes over a module. As previously mentioned, tape tenting may beused to ensure the tape passes sufficiently close to the portion of themodule having the magnetic transducers, preferably such that readingand/or writing is efficiently performed, e.g., with a low error rate.

Magnetic tapes may be stored in tape cartridges that are, in turn,stored at storage slots or the like inside a data storage library. Thetape cartridges may be stored in the library such that they areaccessible for physical retrieval. In addition to magnetic tapes andtape cartridges, data storage libraries may include data storage drivesthat store data to, and/or retrieve data from, the magnetic tapes.Moreover, tape libraries and the components included therein mayimplement a file system which enables access to tape and data stored onthe tape.

File systems may be used to control how data is stored in, and retrievedfrom, memory. Thus, a file system may include the processes and datastructures that an operating system uses to keep track of files inmemory, e.g., the way the files are organized in memory. Linear TapeFile System (LTFS) is an exemplary format of a file system that may beimplemented in a given library in order to enables access to complianttapes. It should be appreciated that various embodiments herein can beimplemented with a wide range of file system formats, including forexample IBM Spectrum Archive Library Edition (LTFS LE). However, toprovide a context, and solely to assist the reader, some of theembodiments below may be described with reference to LTFS which is atype of file system format. This has been done by way of example only,and should not be deemed limiting on the invention defined in theclaims.

A tape cartridge may be “loaded” by inserting the cartridge into thetape drive, and the tape cartridge may be “unloaded” by removing thetape cartridge from the tape drive. Once loaded in a tape drive, thetape in the cartridge may be “threaded” through the drive by physicallypulling the tape (the magnetic recording portion) from the tapecartridge, and passing it above a magnetic head of a tape drive.Furthermore, the tape may be attached on a take-up reel (e.g., see 121of FIG. 1A above) to move the tape over the magnetic head.

Once threaded in the tape drive, the tape in the cartridge may be“mounted” by reading metadata on a tape and bringing the tape into astate where the LTFS is able to use the tape as a constituent componentof a file system. Moreover, in order to “unmount” a tape, metadata ispreferably first written on the tape (e.g., as an index), after whichthe tape may be removed from the state where the LTFS is allowed to usethe tape as a constituent component of a file system. Finally, to“unthread” the tape, the tape is unattached from the take-up reel and isphysically placed back into the inside of a tape cartridge again. Thecartridge may remain loaded in the tape drive even after the tape hasbeen unthreaded, e.g., waiting for another read and/or write request.However, in other instances, the tape cartridge may be unloaded from thetape drive upon the tape being unthreaded, e.g., as described above.

Magnetic tape is a sequential access medium. Thus, new data is writtento the tape by appending the data at the end of previously written data.It follows that when data is recorded in a tape having only onepartition, metadata (e.g., allocation information) is continuouslyappended to an end of the previously written data as it frequentlyupdates and is accordingly rewritten to tape. As a result, the rearmostinformation is read when a tape is first mounted in order to access themost recent copy of the metadata corresponding to the tape. However,this introduces a considerable amount of delay in the process ofmounting a given tape.

To overcome this delay caused by single partition tape mediums, the LTFSformat includes a tape that is divided into two partitions, whichinclude an index partition and a data partition. The index partition maybe configured to record metadata (meta information), e.g., such as fileallocation information (Index), while the data partition may beconfigured to record the body of the data, e.g., the data itself.

Looking to FIG. 9, a magnetic tape 900 having an index partition 902 anda data partition 904 is illustrated according to one embodiment. Asshown, data files and indexes are stored on the tape. The LTFS formatallows for index information to be recorded in the index partition 902at the beginning of tape 906, as would be appreciated by one skilled inthe art upon reading the present description.

As index information is updated, it preferably overwrites the previousversion of the index information, thereby allowing the currently updatedindex information to be accessible at the beginning of tape in the indexpartition. According to the specific example illustrated in FIG. 9, amost recent version of metadata Index 3 is recorded in the indexpartition 902 at the beginning of the tape 906. Conversely, all threeversion of metadata Index 1, Index 2, Index 3 as well as data File A,File B, File C, File D are recorded in the data partition 904 of thetape. Although Index 1 and Index 2 are old (e.g., outdated) indexes,because information is written to tape by appending it to the end of thepreviously written data as described above, these old indexes Index 1,Index 2 remain stored on the tape 900 in the data partition 904 withoutbeing overwritten.

The metadata may be updated in the index partition 902 and/or the datapartition 904 differently depending on the desired embodiment. Accordingto some embodiments, the metadata of the index partition 902 may beupdated in response to the tape being unmounted, e.g., such that theindex may be read from the index partition when that tape is mountedagain. The metadata may also be written in the data partition 902 so thetape may be mounted using the metadata recorded in the data partition902, e.g., as a backup option.

According to one example, which is no way intended to limit theinvention, LTFS LE may be used to provide the functionality of writingan index in the data partition when a user explicitly instructs thesystem to do so, or at a time designated by a predetermined period whichmay be set by the user, e.g., such that data loss in the event of suddenpower stoppage can be mitigated.

As alluded to above, various embodiments are associated with a formatfor magnetic tape recording products and systems. Such format addressesthe need for a configuration that enables higher data rate by allowingmore active transducer channels in use per wrap, but at the same timeprovides backward compatibility to at least a previous generation havingfewer active transducer channels in use per wrap.

Consider, for example, Linear Tape Open, 5^(th) generation (LTO-5),which is a 32 channel format that is backward compatible to LTO-2 andLTO-3, which are an 8 channel format and 16 channel format,respectively. LTO was created at the outset to accommodate both 8 and 16channel formats, and thus enable a transition from 8 to 16 channels, andthen to 32 channels. Continuing with this example, transitioning fromLTO-5 to 64 channels and keeping backward compatibility means the pitchbetween channels needs to be halved again. This creates an asymmetry inthe format, resulting in creation of spare area in a given data band.

“Spare area” may be defined, in some approaches, as area that isnonattainable for user data in the format being used, and is not a guardband positioned adjacent the servo tracks.

In various embodiments, the spare area created by doubling the number ofchannels in, for example, an LTO format is contiguous. In one approach,the spare area that is created is contiguous when, for example, thenumber of channels is doubled in a format wherein the number of activechannels is modulo 4, 8, 16, 32, etc. A spare area is one where all thearea not written to when a data band is fully written occupies one areaof the tape, e.g., as a stripe along the length of the tape. This doesnot include guard bands adjacent the servo tracks. The spare area may becentered in the format, may be placed proximate to servo tracks, or atany point therebetween.

It would be desirable to improve density capability of a magnetic headdesigned to write and read a new high density format while maintainingbackward write and/or read compatibility. Backward compatibility ofmagnetic tape heads to legacy formats is important to the end user ofthe tape drives. Various embodiments described herein enable backwardcompatibility to legacy formats and improve the density capabilityrelative to the legacy format.

According to one embodiment, an apparatus includes an array of 2N+1transducers, where “N” as used herein is an integer greater than zero.The transducers are preferably each individually addressable by thecontroller, e.g., by direct electrical connection between the controllerand each transducer. Accordingly, the controller may include includes2N+1 data channels, each of the data channels being directlyelectrically coupled to an associated one of the transducers e.g., via acable. Thus, no multiplexer is used to select conductive paths to thetransducers in particularly preferred embodiments.

In some embodiments, at least two servo readers are positioned externalto an outermost transducer of the array and on a same side of theoutermost transducer. FIG. 12A et seq., discussed below, depicts severalpotential embodiments having multiple servo readers on a side of thearray of transducers.

Thus, in one embodiment, transducers in a single array are arranged toenable writing and/or reading both a new high density format as well asbeing able to toggle with backward compatibility for writing and/orreading a legacy format.

FIG. 10A depicts a representational view of a preferred embodiment of anapparatus 1000 in the form of an array of transducers of a magnetichead, not to scale, configured to read and/or write to a magneticrecording tape according to a format, in accordance with one embodiment.As an option, the present apparatus 1000 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. Of course, however,such apparatus 1000 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 1000 presented herein may be used in any desired environment.

Referring to FIG. 10, an apparatus 1000 includes an array 1008 of 2N+1transducers, which in this example includes 65 transducers, wheredifferent subsets of the transducers may be activated according toparticular formats, e.g., 64 of the 65 transducers may be activated for64 channel reading or writing. Servo readers S are also shown flankingthe array 1008. The transducers in the array 1008 may be any type oftransducers, such as readers, writers, piggyback reader/writer pairs,merged reader/writer pairs, etc. The servo readers S may include oneservo reader on each side of the array, or multiple servo readers on oneor both sides of the array, e.g., as shown in FIG. 12A.

According to one embodiment, the apparatus 1000 includes the array 1008of transducers, arranged in a single array, including an innertransducer 1012 and subarrays of the transducers positioned on oppositesides of the inner transducer 1012. For example, as shown in FIG. 10B,according to a first mode of operation, the inner transducer 1012 is themiddle transducer, which is inactive in the first mode of operation insome embodiments. The inactive transducer is depicted in FIG. 10B ashaving no fill. The subarrays 1014, 1016 include 32 active datatransducers each (for a total of 64 active transducers) positionedsymmetrically on opposite sides of the inactive inner transducer 1012 inthe first mode of operation.

In many of the foregoing embodiments, the inner transducer 1012 iscentral and the subarrays 1014, 1016 are symmetrically arranged onopposite sides of the inner transducer 1012.

In other embodiments, the subarrays may have differing numbers oftransducers relative to each other. For example, the location of theinactive transducer of FIG. 10B may be shifted to the left or right ofthe centerline, thereby creating asymmetrical arrays. Such location canbe set by the controller 1020.

FIG. 11 depicts a partial view of a preferred embodiment of a product1100 in the form of a magnetic recording tape written by transducers ofthe apparatus 1000 of FIG. 10A in the first mode of operation, asrepresented in FIG. 10B.

Referring to FIG. 11, there is shown a single data band and servo tracks1102 defining the data band therebetween. The format preferablyspecifies modulo an even number, where “modulo” means “a multiple of”,e.g., 2, 4, 8, 16, 32, 64, etc., of active channels and the exampleshown specifies a 64 channel reading and/or writing of data tracks 1104,and formation of spare area 1106 that is centered relative to the datatracks, and correspondingly, generally centered relative to the array oftransducers that read and/or write the data tracks according to theformat, in a direction perpendicular to the tape travel direction. Thislocation of the spare area 1106 is due to the inactive inner transducerbeing located centrally in the array.

When the array 1008 of FIG. 10A is viewed in conjunction with the databand of FIG. 11, it is seen that the spare area 1106 is centeredrelative to the array of transducers. For simplicity, the term “sparearea” on tape may correspond to the inactive region on the magnetichead. Thus, the array in FIG. 10A is logically divided into twosymmetrical subarrays oriented about the inactive region (innertransducer 1012) at the centerline 1022 of the array. This symmetry hasthe advantage that the resultant format is symmetrical, which not onlyfacilitates using the spare area for other functions if desired, butalso greatly simplifies fabrication of the apparatus used for recordingdata in this format, and deployment of that apparatus in a manner thatobviates a need for transducer multiplexing, etc.

Referring again to FIGS. 10B and 11, and the first mode of operation,the array 1008 may have an inactive region 1006 corresponding to thespare area 1106, and positioned between the symmetrical subarrays 1014,1016. For example, the array may not have a transducer in the inactiveregion 1006. Alternatively, an inner transducer 1012 may be present, butis inactive, e.g., not coupled to a cable, damaged, or simply notactivated during operation of the apparatus. The width of the inactiveregion 1006, may be approximately a single width of a data band relativeto a single transducer. However, the resulting spare area on the tapehas a width about equal to a sub-data band (e.g., adjacent trackswritten by a single transducer or otherwise corresponding to the lateralrange of one transducer position in the array). The sub-data banditself, when fully written, may be about equal to the center to centertransducer pitch P₁. Preferably the center to center transducer pitch P₁is the same across the array, i.e., the transducers are equally-spacedon a common pitch.

According to a second mode of operation as represented in FIG. 10C,alternating ones of the transducers in the array are activated, whilethe inner transducer 1012 is inactive. The inactive transducers aredepicted in FIG. 10C as having no fill. Thus, the subarrays 1014, 1016each include 16 active data transducers (for a total of 32 activetransducers) positioned symmetrically on opposite sides of the inactiveinner transducer 1012 in the second mode of operation. The 32 activetransducers in the single array may correspond to a legacy format, e.g.,one having a track pitch that is twice as wide as a modern format.

As shown in FIG. 10A the apparatus also includes a controller 1020 (seealso FIG. 1A, controller 128) coupled to the array 1008 of transducers.The controller may be configured to 1020 determine which mode to use,e.g., based on data on the tape cartridge, information from a database,etc. In response thereto, the controller 1020 may be configured toactivate at least the appropriate transducers and associated datachannels, e.g., as specified by firmware or other logic stored in thecontroller. For example, the controller 1020 may be configured toprocess data (e.g., read or write from the medium) using only thetransducers in the subarrays 1014, 1016 in a first mode of operation andnot the inner transducer 1012. In addition, the controller may beconfigured to process data using only a portion of the transducers ineach of the subarrays in a second mode of operation, not using the innertransducer 1012 as in FIG. 10C, or using the inner transducer, e.g., asin FIGS. 10D and 10E, where the inner transducer 1012 may be active, anda pair of outer transducers on the far end of the array may be inactive(see FIGS. 10D and 10E). The inactive transducers are depicted in FIGS.10D and 10E as having no fill. For example, the modes depicted in FIGS.10D and 10E may be used together, where the mode depicted in FIG. 10Dmay be used for tape travel in one direction, and the mode depicted inFIG. 10E may be used when the tape travels in the other direction. Suchembodiment may enable backward compatibility with existing formats.

Various modes of operation are contemplated, and any subset oftransducers may be selected for a given mode of operation in variousembodiments. For example, all of the data channels, and thus alltransducers, may be active in one mode of operation. In anotherapproach, the controller may be configured to activate data channelsthereof depending on a tape motion direction.

In one exemplary mode of operation, the modes depicted in FIGS. 10F and10G may be used together, where the mode depicted in FIG. 10F may beused for tape travel in one direction, and the mode depicted in FIG. 10Gmay be used when the tape travels in the other direction.

In another example of possible modes of operation, an apparatus havingan array of 2N+1 transducers and controller directly electricallycoupled to each of the transducers is configured to use transducers ononly one side of a centerline of the array in one mode of operation.This may be beneficial because the data elements span approximately halfof the data band, and are therefore less subject to misalignment betweenhead and tape due to tape lateral dimensional instability. Thecontroller may be configured to use transducers on the other side of acenterline of the array in a second mode of operation within the samedata band. The first and second modes may be performed consecutively to,for example, write the entire data band or read the entire data band.

Referring again to FIG. 10A, in various embodiments, a pitch P₂ betweenthe active transducers in the second mode of operation may be anintegral multiple of a pitch P₁ between the active transducers in thefirst mode of operation. In a preferred embodiment, the pitch P₁ betweenthe active transducers in the first mode of operation may be one half ofthe pitch P₂ between the transducers in the second mode of operation,for example, P₁ may be one half the pitch of a legacy pitch.

Looking again to FIG. 11, in one embodiment, the apparatus 1000 may beconfigured to read from and/or write to a magnetic recording tape of aproduct 1100 (e.g., tape cartridge) according to a first format, wherethe first format may specify a number of active channels, locations ofdata tracks 1104 on the magnetic recording tape, and spare area 1106 onthe magnetic recording tape. Furthermore, the first format may alsospecify backward compatibility with a second format, where the secondformat may specify a smaller number of active channels (see e.g., FIGS.10C-10E) than the number of active channels specified by the firstformat (see e.g., FIG. 10B).

In some embodiments of apparatus 1000 where the inner transducer 1012 isnot used for data operations, the inner transducer 1012 may be used as aservo reader to read a servo track for greater positioning accuracy.

In further embodiments, one or more of the transducers within the arrayis configured as a servo reader, e.g., of conventional design. Thetransducer configured as the servo reader may be positioned anywhere inthe array. In one approach, such transducer is flanked by an equalnumber of N transducers on each side thereof.

FIGS. 12A-12E are partial representations of various embodiments of anapparatus 1200, not to scale, configured to read and/or write tomagnetic recording tapes, in accordance with one embodiment. As anoption, the apparatus 1200 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchapparatus 1200 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 1200 presented herein may be used in any desired environment.

In the partial representations of apparatus 1200 in FIGS. 12A-12B, a farend portion of the array of transducers of apparatus 1200 is shown, withtwo servo readers positioned external to an outermost transducer of thearray and on a same side thereof. While the apparatus 1200 may be anyconfiguration of components consistent with the descriptions herein,assume by way of example only that the apparatus 1200 has a similarconstruction as apparatus 1000 of FIG. 10A, and is configured to operatein the first and second modes of operation represented in FIGS. 10B and10C. As shown in FIGS. 12A-12B, the servo reading portion may have twoservo readers 1208, 1210.

Referring to FIG. 12A, in the first mode of operation, both servoreaders 1208, 1210 are active, as well as the adjacent data transducers1214. The servo readers 1208, 1210 may be configured to read a firstservo track 1218 and second and third servo tracks 1220, where thevarious servo tracks may be of any type. The first and second servotracks can be any combination of servo tracks, such as both timing basedservo tracks, one timing based and one HD servo track, etc.

The servo readers 1208, 1210 may be identical, or may be different. Forexample, the servo readers 1208, 1210 may have different track widths.

Referring to FIG. 12B, in the second mode of operation, the apparatus1200 uses 32 active transducers 1214 (of which only one active and twoinactive transducers are shown for simplicity) and only one servo reader1208 to read a servo track 1216 corresponding to the legacy format, forexample, a conventional legacy 32 channel format. In various approaches,the second mode of operation may use one or more of the servo readersfor conventional servo tracks and/or high density servo tracks (notshown). The inactive transducers and servo reader are depicted in FIG.12B as having no fill.

In some embodiments, the apparatus 1000 may be configured to use one orboth of the servo readers 1208, 1210 to read a servo track or tracks asdescribed in U.S. Pat. No. 5,689,384, which is herein incorporated byreference.

In yet other embodiments, the servo reading portion may include three orfour servo readers for reading multiple servo tracks according todifferent formats. FIG. 12C depicts an embodiment having three servoreaders 1208, 1210, 1222 for reading three servo tracks 1218, 1220,1224.

FIG. 12D depicts an embodiment having two servo readers 1208, 1210 onone side of the array for reading three servo tracks 1220, 1226, where,for example, servo track 1220 may be a high density pattern, while servotracks 1226 are timing based servo tracks having a format designed for a32 channel mode of operation. In one approach, the servo tracks 1226 areapproximately half the width and have a steeper chevron angle than aconventional servo track.

The servo tracks read by the plurality of servo readers can be anycombination of servo tracks, such as one or more timing based servotracks, one or more HD servo track, etc. and combinations thereof.

The servo readers 1208, 1210 may be identical, or may be different. Forexample, the servo readers 1208, 1210 may have different track widths.Moreover, the center to center spacing between adjacent servo readersmay be the same or different.

In some embodiments, e.g., as depicted in FIG. 12E, the transducers 1214and servo readers 1208, 1210 are on a module (e.g., as in FIGS. 2A-7),where each of the transducers and servo readers are coupled to anassociated pair of connection pads S1, S2, T1, T2, T3 of the module. Theconnection pads may in turn be coupled to the controller via a flexcircuit (e.g., cable). Referring again to FIG. 12A, noise from fieldscoupling into the leads of the servo reader 1220 positioned closest tothe transducers 1214 may be an issue, especially where the transducers1214 are writers and the servo channel for servo reader 1220 issensitive to noise. If the servo channel for the other servo reader 1208is less sensitive to noise, the relative positions of the pairs ofconnection pads S1, S2 coupled to the servo readers 1208, 1210 may betransposed from relative positions of the servo readers on the module,as represented in FIG. 12F. Accordingly, in the cable, the leads coupledto servo reader 1210 are positioned farther from the leads coupled tothe nearest transducer 1215 than they would be if configured as in FIG.12E.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the array of transducers of a magnetic head, and a controllerelectrically coupled to the array of transducers of a magnetic head.

FIG. 13A depicts a drive-implemented method 1300 for writing and/orreading a first format and a second format in an apparatus, inaccordance with one embodiment. As an option, the method 1300 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such method 1300 and others presented herein may beused in various applications and/or in permutations which may or may notbe specifically described in the illustrative embodiments listed herein.Further, the method 1300 presented herein may be used in any desiredenvironment.

According to one embodiment as illustrated in the flow chart diagram inFIG. 13, a drive-implemented method 1300 begins with operation 1302 thatincludes determining, by the tape drive, that a magnetic recording tapeis compatible with a first format. The tape drive may have an array oftransducers including an inner transducer and subarrays of thetransducers positioned on opposite sides of the inner transducer.

Operation 1304 of method 1300 includes reading from or writing to themagnetic recording tape, by the tape drive, using the array oftransducers in a first mode of operation corresponding to the firstformat. The first format may specify a set of first active channels,locations of data tracks on the magnetic recording tape, and spare areaon the magnetic recording tape. Moreover, the first format may alsospecify compatibility with a second format, e.g., backward compatibilitywith a legacy format. The second format may specify a set of secondactive channels different than the set of first active channelsspecified by the first format.

Operation 1306 of method 1300 includes processing data (e.g., reading orwriting from the medium), by the tape drive, using only the transducersin the subarrays in the first mode of operation and not the innertransducer.

When a tape configured in the second format is operated on by the tepadrive, operation 1308 is performed. Operation 1308 of method 1300includes processing data, by the tape drive, using only a portion of thetransducers in each of the subarrays in the second mode of operation andnot the inner transducer. In other embodiments, operation 1308 includesprocessing data, by the tape drive, using the inner transducer and onlya portion of the transducers in each of the subarrays in the second modeof operation.

In one embodiment, an apparatus includes an array of transducers, wherea total number of the transducers in the array is greater than a numberof transducers specified for a format for which the array of transducersis designed. The apparatus also includes at least two servo readerspositioned together external to an outermost transducer of the array andoptionally at least another servo reader on the other end of the array.The at least two servo readers may include servo readers to read ahigh-density servo pattern and/or a timing-based servo pattern, forexample.

FIG. 13B depicts a drive-implemented method 1350 for writing and/orreading a first format and a second format in an apparatus, inaccordance with one embodiment. As an option, the method 1350 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such method 1350 and others presented herein may beused in various applications and/or in permutations which may or may notbe specifically described in the illustrative embodiments listed herein.Further, the method 1350 presented herein may be used in any desiredenvironment.

Method 1350 includes operations 1302-1306 of FIG. 13A. Operation 1352 ofmethod 1350 includes processing data using at least a portion of thetransducers in each of the subarrays and the inner transducer in thesecond mode of operation.

FIG. 14 depicts a partial view of another embodiment of a product 1400having a magnetic recording tape, in accordance with one embodiment. Asan option, the present product 1400 may be implemented in conjunctionwith features from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. For example, the product1400 may be embodied as a cartridge, such as that shown in FIG. 1A, andhaving a cartridge memory with data therein specifying the format. Ofcourse, however, such product 1400 and others presented herein may beused in various applications and/or in permutations which may or may notbe specifically described in the illustrative embodiments listed herein.Further, the product 1400 presented herein may be used in any desiredenvironment.

Referring to FIG. 14, various embodiments of product 1400 include a databand 1408 and servo tracks 1002 defining the data band therebetween. Theformat of the written tracks preferably specifies modulo an even number,e.g., 2, 4, 8, 16, 32, 64, etc., of simultaneously read or written datatracks, and the example shown specifies a 64 channel reading and/orwriting of data tracks 1004, and formation of spare area 1406 that isproximate to one of the servo tracks 1002, and correspondingly, theservo tracks 1002 may be centered relative to the contiguous group ofdata tracks according to the format, in a direction perpendicular to thetape travel direction. See, e.g., the array in FIG. 15.

FIG. 15 depicts a representational view of an embodiment of an apparatus1500 having an array of transducers, not to scale, configured to readand/or write to a magnetic recording tape according to a format, and acontroller 1020. As an option, the present apparatus 1500 may beimplemented in conjunction with features from any other embodimentlisted herein, such as those described with reference to the other FIGS.Of course, however, such apparatus 1500 and others presented herein maybe used in various applications and/or in permutations which may or maynot be specifically described in the illustrative embodiments listedherein. Further, the apparatus 1500 presented herein may be used in anydesired environment.

The apparatus 1500 includes an array 1508 of transducers, for example,65 transducers as shown, that may include at least one contiguous group1514 of 64 active data transducers and at least two servo readers S. Theservo readers S may be symmetrically positioned about the contiguousgroup 1514 of transducers, and thus are asymmetrically positionedrelative to a Centerline of the array of transducers. Consequently, thecenterline of the servo readers S is located at the center of thecontiguous group 1514 of active transducers and not the Centerline ofthe entire array 1508. For example, as illustrated in FIG. 15, the endtransducer 1512 may be inactive in the array 1508 (e.g. 65 transducersbecome 64 active transducers, 33 transducers become 32 activetransducers, etc.). Thus, the written tracks may be centered in the databand, as illustrated in FIG. 14, thereby creating the spare areas 1406of the data band 1408.

Furthermore, according to another embodiment, the apparatus 1500 hasbackward capability to read and/or write a legacy format including 32active channels toggling format which may use, for example, either theleft-most 32 or right-most 32 of 33 channels centered in the array forwriting and reading the 32 channels.

In a further embodiment, an apparatus includes an array of 2N+1transducers, and a controller electrically coupled only to transducersin odd positions e.g., the N+1, or equivalently the N positions, in thearray. For example, a controller may only be able to communicate with 32or 33 of the 65 transducers of the array of apparatus 1000 of FIG. 10A.The controller has no electrical connection to the other transducers.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Moreover, a system according to various embodiments may include aprocessor and logic integrated with and/or executable by the processor,the logic being configured to perform one or more of the process stepsrecited herein. By integrated with, what is meant is that the processorhas logic embedded therewith as hardware logic, such as an applicationspecific integrated circuit (ASIC), a field programmable gate array(FPGA), etc. By executable by the processor, what is meant is that thelogic is hardware logic; software logic such as firmware, part of anoperating system, part of an application program; etc., or somecombination of hardware and software logic that is accessible by theprocessor and configured to cause the processor to perform somefunctionality upon execution by the processor. Software logic may bestored on local and/or remote memory of any memory type, as known in theart. Any processor known in the art may be used, such as a softwareprocessor module and/or a hardware processor such as an ASIC, a FPGA, acentral processing unit (CPU), an integrated circuit (IC), etc.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

The inventive concepts disclosed herein have been presented by way ofexample to illustrate the myriad features thereof in a plurality ofillustrative scenarios, embodiments, and/or implementations. It shouldbe appreciated that the concepts generally disclosed are to beconsidered as modular, and may be implemented in any combination,permutation, or synthesis thereof. In addition, any modification,alteration, or equivalent of the presently disclosed features,functions, and concepts that would be appreciated by a person havingordinary skill in the art upon reading the instant descriptions shouldalso be considered within the scope of this disclosure.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A drive-implemented method, comprising: determining, by a tape drive, that a magnetic recording tape is compatible with a first format, the tape drive having an array of transducers including an inner transducer and subarrays of the transducers positioned on opposite sides of the inner transducer; reading from or writing to the magnetic recording tape, by the tape drive, using the array of transducers in a first mode of operation corresponding to the first format, wherein the first format specifies locations of data tracks on the magnetic recording tape, and a contiguous spare area on the magnetic recording tape, wherein the first format also specifies compatibility with a second format, wherein the second format specifies a set of second active channels different than a set of first active channels specified by the first format; processing data, by the tape drive, using only the transducers in the subarrays in the first mode of operation; and processing data, by the tape drive, using only a portion of the transducers in each of the subarrays in a second mode of operation corresponding to the second format.
 2. The drive-implemented method of claim 1, wherein the tape drive has at least two servo readers positioned external to an outermost transducer of the array of transducers and on a same side thereof.
 3. The drive-implemented method of claim 2, wherein the at least two servo readers are configured to read a combination of servo tracks.
 4. The drive-implemented method of claim 3, wherein a first of the servo readers is configured to read a first servo track having a first servo format, wherein a second of the servo readers is configured to read a second servo track having a second servo format, wherein the first servo format and the second servo format are different.
 5. A computer program product for writing and/or reading a first format and a second format in an apparatus, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions executable by a processor to cause a tape drive to: determine, by a tape drive, that a magnetic recording tape is compatible with the first format, the tape drive having an array of transducers including an inner transducer and subarrays of the transducers positioned on opposite sides of the inner transducer; read from or write to the magnetic recording tape, by the tape drive, using the array of transducers in a first mode of operation corresponding to the first format, wherein the first format specifies locations of data tracks on the magnetic recording tape, and a contiguous spare area on the magnetic recording tape, wherein the first format also specifies compatibility with the second format, wherein the second format specifies a set of second active channels different than a set of first active channels specified by the first format; process data, by the tape drive, using only the transducers in the subarrays in the first mode of operation; and process data, by the tape drive, using only a portion of the transducers in each of the subarrays in a second mode of operation corresponding to the second format.
 6. A drive-implemented method, comprising: determining, by a tape drive, that a magnetic recording tape is compatible with a first format, the tape drive having an array of transducers including an inner transducer and subarrays of the transducers positioned on opposite sides of the inner transducer; reading from or writing to the magnetic recording tape, by the tape drive, using the array of transducers in a first mode of operation corresponding to the first format, wherein the first format specifies a set of first active channels, locations of data tracks on the magnetic recording tape, and spare area on the magnetic recording tape, wherein the first format also specifies compatibility with a second format, and wherein the second format specifies a set of second active channels different than the set of first active channels specified by the first format; processing data, by the tape drive, using only the transducers in the subarrays in the first mode of operation; and processing data, by the tape drive, using at least a portion of the transducers in each of the subarrays and the inner transducer in a second mode of operation.
 7. The drive-implemented method of claim 6, wherein the tape drive has at least two servo readers positioned external to an outermost transducer of the array of transducers and on a same side thereof.
 8. The drive-implemented method of claim 7, wherein the at least two servo readers are configured to read a combination of servo tracks.
 9. The drive-implemented method of claim 8, wherein a first of the servo readers is configured to read a first servo track having a first servo format, wherein a second of the servo readers is configured to read a second servo track having a second servo format, wherein the first servo format and the second servo format are different. 